Air or gas compressor



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AIR OR (ms COMPRESSOR Filed Dec. 4, 1934 s Sheets-Sheet 2 L Y L M. A.TWESLETON-WYK QEHAM-FHENNES Ell A AIR OR GAS COMPRESSOR PRIME MOVER MAumca AL Bar/c TWISLETON-WWEHA M- WEN/v53,

ERWEWHEWY 5M5 TGER.

.A TTO/QA/EX Patented Apr. 7, 1936 UNITED STATES PATENT OFFICE AIR ORGAS COMPRESSOR Maurice Alberic Twisleton-Wykeham-Fiennes ish companyApplication December 4, 1934, Serial No. 755,994 In Great Britain May24, 1933 11 Claims.

This invention relates to air or gas compressors of the reciprocatingtype, and of the kind in which the adjacent ends of two or morecylinders are interconnected by a valve controlled passage 5. orpassages, the said valve or valves being in turn so controlled that onthe pressure generated in the receiver attaining a predetermined figurethe valve controlling the passage or passages opens and the air or gassurges to and fro between the 10 said cylinders, while when the pressurefalls below the said predetermined pressure the valve closes.

To enable a compressor to operate efficiently the clearance volumethatis to say the volume 15 of the space enclosed between the inner ends ofthe pistons at their inner stroke limits, the inner ends of thecylinders, the inlet and outlet valves and the unloading valve orvalvesmust be reduced to a minimum so that the amount of compressed airremaining in a cylinder at the end of the delivery stroke is at aminimum. Hence any unloading means employed must be such that anyincrease in the clearance volume it may necessitate is as small aspossible.

25: The object of the present invention is to provide unloading meanswhich will enable the length of the passages between the cylinders andthe unloading means to be a minimum with a view to reducing theclearance volume to a minimum,

30 and, if desired, allow the cylinders tobe arranged as close togetheras possible where compactness is necessary, without restricting thecross sectional area or volume of the inter-connecting passages betweenthe cylinder working spaces.

35 Another object of the invention is to provide improved unloadingmeans which may be used with a compressor of any desired number ofcylinders and give simultaneous unloading between the various cylindersso that the possibility 40 of time lag occurring between differentcylinders unloading may be positively eliminated, or alternatively, theunloading between different sets of cylinders effected in stages.

A further object of the invention is to provide 45 an improved controlof the unloading means which control shall be positive in its action andentirely free from hunting.

According to the invention the unloading valve comprises a singlemovable valve member which 50 on the one hand and the cylinders on theother hand are arranged substantially tangential to each other adjacentthe clearance space, and having its axis substantially parallel with theaxis of the compressor crankshaft.

For unloading in stages, two cylinders having pistons connected tocranks spaced at 180 or three cylinders having pistons connected tocranks spaced at 120 may be interconnected.

With a view to reducing the clearance volume to a minimum, the length ofthe passage or passages communicating between the cylinder or cylindersand the valve means is a minimum.

The invention will now be described by way of example with reference tothe accompanying drawings which show its application to the cylinders ofa two-cylinder compressor.

In the said drawings:

Fig. 1 is an elevation partly in section showing the unloading deviceand its control means in section.

Fig. 2 is a side view of Fig. 1.

Fig. 3 is a sectional plan of Fig. 2 taken on the line III--III of Fig.2.

Fig. 4 is an enlarged view of a portion of Fig. 1.

Fig. 5 is an enlarged View of the pilot valve and shows its connectionwith engine throttle.

Fig. 6 is a sectional plan similar to Fig. 3 but showing an axiallymovable unloading valve.

Fig. '7 is a fragmentary sectional elevation of a suction portcontrolled by a pilot valve.

Fig. 8 is a view in elevation of a compressor adapted for unloading instages.

Fig. 9 is a view in elevation of a pilot valve adapted for two stageunloading.

Fig. 10 is a semi-diagrammatic section of the port arrangements of thepilot valve shown in Fig. 9.

Fig. 11 is a detail view of an unloading valve for unloading in stages.

Referring more particularly to the drawings, a compressor is shownhaving a crank shaft llll and compressor cylinders l and 2, which areconnected by separate passages 3, 4 to a transfer passage 5 in an inletmanifold 6. A common hollow unloading valve 1 is located in a bore whichintersects the passages 3 and 4, which are thus controlled by the saidvalve. The valve 1 being hollow itself also provides a connectingpassage in addition to the passage 5. The valve 1 has rigid therewith anarm 8 the free end of which engages in a slot formed in the middle of adouble ended piston 9 adapted to work in a cylinder Ill secured to thecompressor cylinders.

Each end of the cylinder I0 is connected to a casing II in which aweighted pilot valve I2 is adapted to move up and down so as toestablish communication with either the upper or lower end of thecylinder Ill according to its position in the casing I I. Theconnections between the easing and the cylinder [0 comprise pipes l3, I4

fill

' pipe 33 to the engine throttle control.

connected to longitudinally spaced ports l5, IS in the casing l l, thecasing l I being connected to the air receiver (not shown) through aport H between the ports l5, l6. Opposite the port l5, which controlsthe flow of air to move the valve 1 to the unloading position, is a port48 connected to a cylinder in which is a piston operatively connected tothe throttle control of the engine driving the compressor.

With this arrangement when the air pressure in the receiver reaches apredetermined limit, the pilot or control valve i2 is lifted and soallows live air to fiow through the port E6, pipe I4, and enter thelower end of the cylinder i3 and raise the piston 9 so that the valve '3is turned into the unloading position. Simultaneously pressure air flowsthrough the port 8 to operate a spring piston 48 connected with theprime mover throttle 49 and causes the power of the prime mover drivingthe compressor to be reduced.

An adjustable needle valve [9 (see Figs. 1 and 4) is provided in theupper end of the cylinder I8 so that the rate of flow from the pipe l3into the cylinder [9 may be varied at will.

By making the control valve [2 weight controlled instead of springcontrolled, the action of the valve is rendered more definite so thathunting such as occurs with a spring controlled valve is avoided.

Fig. 6 shows an alternative form of the invention in which the unloadingvalve comprises an axially movable valve 2|. The piston 9 is dispensedwith and the live air taken through the pipes 22 connected with thepilot valve to each end of the valve casing 23.

Fig. 7 shows a modification wherein the inlet air suction 24 is closedsimultaneously with the opening of the unloading valve. This isefifected by connecting the control valve pneumatically to the one sideof a piston 26 which at the unloading pressure is moved across the inletport 24 of the compressor against the action of a spring 27 or weight.This has the advantage of lowering the pressure in the cylinder orcylinders by reason of the fact that air is completely shut off.

Instead of unloading the cylinders simultaneously, it may be desirableto unload by stages, that is to say at a given receiver pressure onegroup of cylinders only unloads. This may be efiected, for example, byproviding an additional pilot valve or valves adapted to operate at apressure or pressures other than the normal unloading pressure. In thearrangement shown in Fig. 8 a four-cylinder compressor is shown, thecylinders of which are grouped in two pairs A, B. The pair A arecontrolled by a separate unloading valve 29 and the pair B by a separateunloading valve as. The said unloading valves are identical with thatshown in Figs. 1 to 3 so that it is not necessary to show these indetail again. The valve 29 is operated by a pilot valve 3i exactly as inthe arrangement shown in Figs. 1 to 4, the pipe 32 being connected tothe receiver and the The valve 30 is similarly operated by a secondpilot valve 34 which is connected by the pipe 35 to the receiver, and isloaded with less weight that is the pilot valve 3| so that it operatesthe valve 39 at a lower receiver pressure than that required to operatethe valve 29.

Alternatively such stage unloading may be effected by means of a pilotvalve which has more than one operative position according to thepressure in the receiver. For this purpose the unloading valve may havean additional port or ports adapted to be placed in communication withthe desired group or groups of clearance spaces at the lower receiverpressure or pressures corresponding to the first stage or stages ofunloading. Such a pilot valve and unloading valve are shown in Figs. 9,l0, 11, in which 36 is the movable member of the pilot valve and 3'! thepilot valve casing. The first stage of the unloading is controlled bythe lower portion of the pilot valve, the pipe 38 being connected to thereceiver and the pipes 39, 46 to the two ends of the unloading valvecasing or the casing of the piston operating the unloading valve. Thesecond stage of the unloading is controlled by the upper portion of thepilot valve, the pipe 4| being connected to the receiver and the pipes42, 43 to the unloading valve casing or the casing of the pistonoperating the said valve. Holes 44, 45, 46 are formed in the casing 3'!for exhaust purposes, the hole 45 being common to both portions of thevalve 36. At the first stage of the unloading the weight 50 is raised bythe valve 36, the said weight being threaded in an extension 36a of thesaid valve. The extension 35a passes through a bush 5| flanged at itslower end at Eta and supported in a bracket 52 rigid with the valvecasing 31. A second weight 53 is threaded on the bush El and rests onthe flange 51a, so that on the first stage of unloading taking place themovement of the valve 36 is arrested when the weight 50 abuts againstthe weight 52. When the receiver pressure rises to that predeterminedupon for the second stage of unloading the weight 52 is raised with theweight 50.

The unloading valve is a single member 4'! controlling the two pairs ofcylinders and is shown in Fig. 11. The ports 41a therein are the firststage unloading ports and affect the one pair of cylinders only. Fourports 411) are the second stage unloading ports. The said ports 47?) arespaced circumferentially from the ports 47a and are in alignment withone another so as to eifect simultaneous unloading of all cylinders.

Fig. 9 shows diagrammatically the arrangement of the various pipes, fromwhich it will be seen that after a certain amount of movement of thevalve 36 communication is established between the pipes 38 and 39 andthe unloading valve 41 is rocked so that first the ports 41a establishcommunication between the one pair of cylinders and so effect the firststage of unloading. Further movement of the pilot valve 38 establishescommunication between the pipes 4! and 42 and so causes further movementof the unloading valve 41 with the result that the ports 4Tb establishcommunication between all the cylinders and effeet the second stage ofunloading.

It will be seen that with the arrangement according to the invention theunloading means is freely accessible, and also allows of the unloadingvalve being effectively cooled (1) on account of its being situated in arelatively cool position and (2) as its accessible position allows ofits being thoroughly water jacketed. Again, it will be seen that in acompressor according to the invention having a number of interconnectedcylinders and a common valve, all the transfer ports may be arranged toopen simultaneously, so that all possibility of lag between the times ofopening of the transfer ports is eliminated, or the said ports may bearranged to open consecutively. Further, on account of the accessibilityand arrangement of the unloading valve, means communicating with thesaid cylinders, a pilot may be provided thereon as at whereby the valvemay be manually operated at will.

We claim:

1. A multi-cylinder fluid compressor of the kind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders and said cylinders on the one hand andsaid valve means on the other hand being arranged substantiallytangential to each other adjacent the clearance space, and said valvemeans having its axis substantially parallel with the axis of thecompressor crank shaft.

2. A multi-cylinder fluid compressor of the kind described comprising,in combination, a. plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading -ders viewed. in thedirection of the axes of said cylinders adjacent the clearance space andhaving its axis substantially parallel with the axis of the compressorcrankshaft.

3. A multi-cylinder fluid compressor of the kind described comprising,in combination, a

plurality of cylinders, passage means interconnecting the interiors ofsaid cylinders, unloading means adapted to control said passage means,

said unloading means comprising valve means adapted to control aplurality of cylinders, said cylinders on the one hand and said valvemeans on the other hand being arranged substantially tangential to eachother adjacent the clearance space and said valve means having its axissubstantially parallel with the axis of the compressor crankshaft, thesaid valve being adapted to effect simultaneous unloading of allcylinders.

l. A multi-cylinder fluid compressor of the kind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders, said cylinders on the one hand andsaid valve means on the other hand being arranged substantiallytangential to each other adjacent the clearance space and said valvemeans having its axis substantially parallel with the axis of thecompressor crankshaft, the said valve being adapted to effect unloadingof all cylinders in stages.

5. A multi-cylinder fluid compressor of the kind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising axially movable valvemeans adapted to control a plurality of cylinders, said cylinders on theone hand and said valve means on the other hand being arrangedsubstantially tangential to each other adjacent the clearance space, andsaid valve means having its axis substantially parallel with the axis ofthe compressor crankshaft, a receiver valve adapted to be operated bypressure air from said receiver, and passage means from said pilot valveadapted to take live air to each end of said axially movable valve meansto operate said axially movable valve means according to the position ofsaid pilot valve.

6. A multi-cylinder fluid compressor of the kind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders, said cylinders on the one hand andsaid valve means on the other hand being arranged substantiallytangential to each other adjacent the clearance space, and said valvemeans having its axis substantially parallel with the axis of thecompressor crankshaft, a receiver connected to the cylinders, a pilotvalve adapted to be operated by pressure air from said receiver, passagemeans from said pilot valve to said unloading means, such that on,operation of the said pilot valve pressure air is admitted to saidunloading means to actuate the movable valve means, means for drivingsaid compressor, control means on said driving means, a pneumaticoperating device connected to said control means, a further passagemeans connecting said pilot valve to the id pneumatic device, so thatwhen a pilot valve 1. in the position to open said unloading means thepower of said driving means is reduced.

7. A multi-cylinder fluid compressor of the kind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading m ans adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders, said cylinders on the one hand andsaid valve means I on the other hand being arranged substantiallytangential to each other adjacent the clearance space, and said valvemeans having its axis substantially parallel with the axis of thecompressor crankshaft, an inlet air suction port, and means whereby thesaid suction port may be opened and closed simultaneously with theopening of the unloading means.

8. A multi-cylinder fluid compressor of the kind described comprising,in combination, a p1urality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders, said cylinders on the one hand andsaid valve means on the other hand being arranged substantiallytangential to each other adjacent the clearance space, and said valvemeans having its axis substantially parallel with the axis of thecompressor crankshaft, an inlet air suction port, means whereby saidsuction port may be opened and closed simultaneously with the opening ofthe unloading means, a receiver, a pilot valve adapted to be operated bypressure air from the said receiver, passage means from said pilot valveto said unloading means, a compressor inlet port, a cyl nder, and insaid cylinder a piston adapted for movement across said inlet port,restoring means adapted to act on said piston, and passage meansconnecting said pilot valve with said cylinder, so that at unloadingpressure said piston is moved across said inlet port.

9. A multi-cylinder fluid compressor of the kind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders, said cylinders on the one hand andsaid valve means on the other hand being arranged substantiallytangential to each other adjacent the clearance space, and said valvemeans having its axis substantially parallel with the axis of thecompress r crankshaft, a receiver connected to said cylinders, aplurality of pilot valves adapted to be operated by pressure air fromsaid receiver, passage means from said pilot valves to said unloadingmeans such that on operation of the said pilot valves pressure air isadmitted to said unloading means to actuate the movable valve means atdifferent unloading pressures.

10. A multi-cylinder fluid compressor of the kind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders, said cylinders on the one hand andsaid valve means on the other hand being arranged substantiallytangential to each other adjacent the clearance space, and said valvemeans having its axis substantially parallel with the axis of thecompressor crankshaft, a receiver connected to said cylinders, a pilotvalve adapted to be operated by pressure air from said receiver, passagemeans from said pilot valve to said unloading means, such that onoperation of said pilot valve pressure air is admitted to said unloadingdevice to actuate the movable valve means, said pilot valve having aplurality of operative positions according to the pressure in saidreceiver.

11. A multi-cylinder fluid compressor of the ind described comprising,in combination, a plurality of cylinders, passage means interconnectingthe interiors of said cylinders, unloading means adapted to control saidpassage means, said unloading means comprising valve means adapted tocontrol a plurality of cylinders, said cylinders on the one hand andsaid valve means on the other hand being arranged substantiallytangential to each other adjacent the clearance space, and said valvemeans having its axis substantially parallel with the axis of thecompressor crankshaft, a receiver connected to said cylinders, a pilotvalve adapted to be operated by pressure air from said receiver, passagemeans from said pilot valve to said unloading means, such that onoperation of said pilot valve pressure air is admitted to said unloadingdevice to actuate the movable valve means, said pilot valve having aplurality of operative positions according to the pressure in saidreceiver and additional ports in said unloading means adapted toestablish communication between groups of cylinders at the variousreceiver pressures.

MAURICE ALBERIC TWISLETON- WYKEHAM-FIENNES. ERNEST HENRY SWEETSER.

